Thanks David - all the updates have been made to the latest draft. I
will wait until the current review period ends and then re-publish,
along with any other comments or feedback we may receive.

Cheers

Pieter

On Wed, Dec 10, 2025 at 8:43 PM David Mandelberg <[email protected]> wrote:
>
> Op 2025-12-08 om 09:58 schreef Pieter Kasselman:
> > The text already addresses the "neighbouring country" problem with IP
> > addresses, so I'll leave that as is.
>
> I think places like Svalbard and Antarctica are different from
> neighboring countries, because they can have countries that don't share
> any border operating in the same place. I have no idea how that impacts
> IP geolocation though, and I don't think either place has a large
> population, so it might not be worth worrying about.
>
> Thinking about it more, this feels like something that's probably out of
> scope for this document, but maybe should be handled elsewhere by
> something that lists as many limitations of IP geolocation as possible.
>
> > Regarding the whiteboard example, in theory access could be limited to
> > displaying files, but displaying files also requires access to them and
> > assumes a level of fine-grained access control that is not typically
> > implemented. Access is often granted at the directory or repository
> > level (or repositories), not on a per-file basis. The degree of access
> > is dictated by the Acccess Token and and it is not unheard of that the
> > token obtained from such a flow would give much broader access than just
> > allowing files to be displayed (overprivileged tokens are often used in
> > lateral moves for example). Consequently relying on the scope of access
> > as a mitigation to allow for the use of Device Authorization Grant is
> > problematic.
> >
> > In terms of protocols, both CIBA and Device Authorization grant are
> > exploitable in the context of cross-device flows. Of the two, Device
> > Authorization Grant has proven to be more easily and commonly exploited.
> >
> > The attack you describe in the context of CIBA is possible, but it is
> > much more specific and narrowly scoped compared to all the attacks that
> > become posssible if a system use Device Authorization Grant instead.
> > Device Authorization Grant opens up different and more commonly
> > exploited attacks.
> >
> > In general CIBA is harder to exploit than Device Authorization Grant. In
> > the context of the attack you describe, it raises the bar for the
> > attacker regarding timing and the scale of execution (targeting one vs
> > targeting millions simultaneously) compared to the attacks against the
> > Device Authorization Grant. Sometimes the best we can do is to raise the
> > bar and choose the options that are harder to exploit. I have come to
> > think of these trade-offs as "lesser of evils" exercises... FIDO with
> > WebAuthn is your safest bet if you need cross-device authentication and
> > authorization.
>
> Makes sense. I think CIBA's security could be improved by showing the
> same code on both devices and telling the user to compare them, but
> maybe all the use cases that would benefit from that should just use
> FIDO instead.

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